How Do We Teach TDD Keith Ray
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The document discusses teaching Test-Driven Development (TDD) using the Dreyfus model of learning, which outlines five levels of skill acquisition from novice to expert. It highlights the challenges in teaching TDD due to the complexities involved in writing tests, code, and refactoring, as well as the need for fast feedback for novices. The approach includes web-based materials, live training, and coaching, emphasizing the benefits of peer pairing and continuous assessment to enhance learning.
![TDD seems so simple, so why
is it hard to teach?
Teacher: it's red, green, refactor, repeat.
<long time later>
Student: here's my first test. [400 lines of code
in a single test.]
Photo by Marcin Wichary](https://image.slidesharecdn.com/howdoweteachtddkeithray-110330132222-phpapp01/85/How-Do-We-Teach-TDD-Keith-Ray-10-320.jpg)
How Do We Teach TDD Keith Ray
- 1. How Do We Teach TDD? Considering the Dreyfus Model of Learning C. Keith Ray Coach, Trainer, Developer at Industrial Logic, Inc. [email protected] twitter: @ckeithray http://industriallogic.com
- 2. What's TDD? TDD is Test-Driven Development. The simple description of TDD is: Red-Green-Refactor-Repeat: write a test that fails (red), write just enough code to make it pass (green), then refactor to a good design (aka "simple code"), and repeat.
- 3. Dreyfus Model Dreyfus came up with a model of learning. He named five levels: Novice Advanced Beginner Competent Proficient Expert See http://en.wikipedia.org/wiki/Dreyfus_model_of_skill_acquisition
- 4. Novice Completely new to the thing to be learned. Wants recipes, rules, constraints They don't know what "good" look likes yet, so they want fast feedback. Craves rules.
- 5. Advanced beginner Knows the rules, but not all the contexts for them, knows just enough to be "dangerous." As a software developer, probably writing "big balls of mud". Better to have them learning in a safe environment to learn from their mistakes. 5
- 6. Competent Can do a task without needing instructions. Identifies patterns and uses them, mostly in appropriate contexts. May be offended if you treat them like a Novice or Advanced Beginner.
- 7. Proficient Good, but now trying to become expert. Lots of experience / practice. Knows how to do stuff, but can't tell people how to do it. (Teaching has its own Novice to Expert levels)
- 8. Expert Beyond rules. Working on instinct. Needs to compare notes with other experts. Arguing about their subject refines their understanding of it.
- 9. TDD seems so simple, so why is it hard to teach? Teacher: it's red, green, refactor, repeat. <long time later> Student: ok, here's all my tests! Teacher: where's the code? Student: I haven't written it yet. Teacher: Photo by striatic
- 10. TDD seems so simple, so why is it hard to teach? Teacher: it's red, green, refactor, repeat. <long time later> Student: here's my first test. [400 lines of code in a single test.] Photo by Marcin Wichary
- 11. TDD seems so simple, so why is it hard to teach? Teacher: it's red, green, refactor, repeat. Student: <Doesn't understand why the test should fail before it is made to pass, so writes code and tests so that the tests usually pass the first time they are run.> oops
- 12. TDD seems so simple, so why is it hard to teach? Teacher: it's red, green, refactor, repeat. Student: here's my tests and code. Teacher: nice, but you've got a very large class, with a very large method, and all your tests are repeating lots of code. Did you refactor? Student: I thought we'd refactor next month!
- 13. TDD seems so simple, so why is it hard to teach? Because each of the steps of TDD require skills in three main areas: Writing tests. Writing simple code. Refactoring.
- 14. There's more, Refactoring Requires: Recognizing symptoms of bad design (code smells). Making small transformations to improve the design. (The actual Refactorings.) Recognizing good design (aka "Simple Code")
- 15. "Simple Design" Kent Beck's rules for simple design were: 1. Runs all the tests. 2.No duplication. 3. Expresses the developer's intentions. 4.Minimizes the number of classes and methods. Photo by GN
- 16. Getting back to Dreyfus... We teach using web-base materials in live training and via coaching. Our web-based materials assume the student is in the Novice stage of learning about TDD. We also assume the student is at least in the Competent stage as a programmer. We encourage pairing of students — it makes a large improvement in learning.
- 17. What Novices Want A "novice" is completely new to a subject. They want rules, recipes, formulas, step-by-step how-to-do-it. They don't know enough to judge their own results, so they need fast, frequent feedback by coach or trainer. Photo by Steve Snodgrass
- 18. Breaking TDD Skill-Sets into Novice-sized Pieces
- 19. Demo Video Videos are usually short (around 5 minutes) and demonstrate a technique or make a point.
- 20. Demo Quizzes We have a variety of quiz types. Students can comment on quiz answers or post questions and get a prompt response from Industrial Logic staff.
- 21. Demo: Exercises TDDing Big Bill's Billing System Task 1: Calculate A Simple Phone Bill Task 2: Calculate Excess Minutes Task 3: etc. Student writes the code, compares it with solution(s). Almost all solutions are demonstrated in video form and downloadable code.
- 22. Demo: Critiques Your score was 62% based on our Automated Critique. This ranks you as Intermediate. A Graph of Your TDD Activity See several examples here.
- 23. Conclusion Our web-based training with critiques provides feedback that Novices and Advanced Beginners need, and which would otherwise require one-to-one coaching. This works for our live training as well as purely web-based training. Try it out: http://elearning.industriallogic.com (PS: Competent, Proficient, and TDD Experts should try Sessions.) See also Dan North appling the Dreyfus model to a more general level of "best practices": http://www.infoq.com/articles/better-best-practices